Portable computers, including those known as laptops, notebooks and palmtops, usually have a display screen housing that is hinged to a base part which carries the keyboard. The display housing is movable about the hinge(s) between a closed position against the base part and an open position with the display and keyboard exposed for use.
The hinges typically incorporate mechanisms that rely on friction to hold the display housing in the open position at the angle relative to the computer base preferred by the user.
The friction required by the hinge mechanism to support the weight of the display housing may be so great that two hands are required to open the computer. A user must use one hand to hold the base while using the other hand to pivot the display about the hinge. Furthermore, the display housing has a tendency to slam closed against the computer base.
In accordance with one aspect of the present invention, a hinge assembly for a device, such as a portable computer, is provided with a clutch mechanism that includes a friction component and a torsion spring component. The spring counteracts the weight of the display housing of the open computer. In this way, the friction component of the clutch mechanism need only be strong enough to support the open display housing during times when the computer is subjected to vibration or the like. This solution reduces the amount of force necessary to adjust the angular position of the display housing. One hand may be used to open and close the device. The reduced friction force allows use of a smaller, lighter friction component.
As another aspect of this invention, the weight-counteracting effect of the torsion spring-tends to prevent the display from inadvertently or accidentally slamming closed against the base.
As another aspect of this invention, the pivot shaft has an inner surface of a sufficient diameter to allow a cable to pass through at least one of the hinge assemblies to carry electronic signals between the display and the base.